From: | Wei Weng <wweng(at)kencast(dot)com> |
---|---|
To: | Bruno Wolff III <bruno(at)wolff(dot)to> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: How do you compare (NULL) and (non-NULL)? |
Date: | 2004-10-29 15:59:15 |
Message-ID: | 418268D3.3080700@kencast.com |
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Thread: | |
Lists: | pgsql-sql |
Bruno Wolff III wrote:
> On Tue, Oct 26, 2004 at 16:23:20 -0400,
> Wei Weng <wweng(at)kencast(dot)com> wrote:
>
>>In the following query
>>
>>SELECT Parent FROM Channels ORDER BY Parent ASC;
>>
>>If I have a couple of (NULL)s in the field [Parent], they will be listed at
>>the bottom of the query result.
>>
>>Is it because PostgreSQL considers (NULL) as the biggest value? If I run
>>the same query under MSSQL Server 2000, I get the exact opposite result
>>regarding the order of (NULL)s and (non-NULL) values. They are listed at
>>the very beginning of the query result.
>
>
> If the order matters, you can order by IS NULL or IS NOT NULL.
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
>
>
How do I write that?
Thanks
Wei
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